1. Field of the Invention
The present invention generally relates to a burn rate control valve for gas fired heaters in the form of a 1/4 turn ball valve having two flow passages through the valve member in which one flow passage is for full gas flow and the other flow passage is smaller in diameter for low gas flow in order to provide a full burn rate or a low burn rate. The two passages are dimensioned and angularly related such that the larger or full burn rate passage essentially provides unrestricted flow when aligned with related ports or piping with the smaller or low burn rate passage being angularly related to the larger passage at an angle less than 90.degree. in order to maintain a flow passageway when the ball valve member is moved to a position with the larger passage perpendicular to the associated ports. This angular relation assures that the smaller flow passage will be opened before the larger flow passage closes too much in order that the burner will not cease to operate and not provide a lower burn rate than intended.
2. Description of the Prior Art
Gas fired heaters are generally well known and have been in use for many years. One desirable feature of such heaters is the ability to operate over a range of burn rates. Typical gas fired heaters of this type are disclosed in U.S. Pat. No. 3,494,599 issued Feb. 10, 1970 for Portable Forced Air Heater; U.S. Pat. No. 3,645,512 issued Feb. 29, 1972 for Forced Air Heater and U.S. Pat. No. 4,244,349 issued Jan. 13, 1981 for Portable Forced Air Heater. Gas fired heaters such as disclosed in the above patents have the ability to operate over a range of burn rates. The burn rate can be controlled by throttling the gas flow to the fuel orifice of such heaters. Two methods of controlling the burn rate is to (1) use a variable pressure regulator in the gas supply line or (2) use a valve in the fuel supply line.
While burn rate variation is known, the prior art does not include this invention in which a variable burn rate gas fired heater has the burn rate controlled by the unique structure of a 1/4 turn ball valve incorporated into the gas fuel supply line between the gas pressure regulator and a fixed size heater fuel orifice.